Gas-filled discharge tube impulse control and operating apparatus



R. DEssouLAvY ETAL 3,514,667 GAS-FILLED DISCHARGE TUBE IMPULSE CONTROL May 26, 1970 AND OPERATING APPARATUS 4 Sheets-Sheet 1 Filed May 23 1968 /n van turs.. 79,90 @S500/a 775/# a/ g v/a J) R. DEssouLAvY ETAL 3,514,667 GAS-FILLED DISCHARGE TUBE IMPULSE CONTROL May 26, 1970 AND OPERATING APPARATUS 4 Sheets-Sheet 2 Filed May 23 1968 qvh Z Zzi 252i Z3 Inventors: -/Pf Z'rsaa/aay mwra/Lr fw/a 3f May 26, 1970 R. DESSOULAVY ErAL 3,514,667

GAS-FILLED DISCHARGE TUBE IMPULSE CONTROL AND OPERATING APPARATUS Filed May 23 1968 4 Sheets-Sheet ."5

CONTROLL ABLE /n an tors May 26, 1970 R, DESSQULAVY ETAL 3,514,667

GAS-FILLED DISCHARGE TUBE IMPuLsE CONTROL AND OPERATING APPARATUS Filed May 23 1968 4 Sheets-Sheet 4 mw Q l I i /n ven tors /vff @5500/050 7970x6224 a/a United States Patent O 3,514,667 GAS-FILLED DISCHARGE TUBE IMPULSE CONTROL AND OPERATING APPARATUS Roger Dessoulavy, Lausanne, and Francois Riolo,

Territet, Switzerland, assignors to Bron Elektronik Aktiengesellschaft, Basel, Switzerland Filed May 23, 1968, Ser. No. 731,413

Claims priority, application Germany, May 24, 1967,

Int. Cl. Gf 1/50; IIOSb 37/02, 39/04 U.S. Cl. 315-194 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a feeding apparatus for operating by impulses at least one gas-filled discharge tube, especially a Xenon tube, and a discharge tube for use in connection with such apparatus.

Discharge tubes filled with rare gases, especially Xenon tubes, operate particularly advantageously when operated in an impulse circuit. In this connection, principally a condenser is periodically through the intervention of an inductance charged from an electric network, and subsequently the stored charge is discharged through the discharging tube. Inasmuch as the discharging tube with each discharging operation has again to be ignited, it is, as a rule, necessary to include a high voltage transformer in the discharge circuit for producing the ignition Voltage.

Apparatus built in conformity with this principle has a drawback of being heavy, bulky, and expensive in production, said drawbacks being primarily due to the required condensers and chokes. Moreover, the high voltage impulses passed through the feeding lines for the tubes transfer with the ordinary radio waves. In some instances it is furthermore disadvantageous that the discharge tubes in these known circuits either can be only fully turned on or fully turned off and therefore do not permit a control of the light intensity. Moreover, the light intensity greatly depends on the respective voltage of the electric network.

It is, therefore, an object of the present invention to provide a simple and easily transportable feeding apparatus of the above mentioned general type, which will avoid the drawbacks outlined above.

It is another object of this invention to provide an apparatus as set forth in the preceding paragraph which will permit a change in the respective light intensity of the discharging lamp, or discharging lamps, in a simple manner.

These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:

FIG. 1 illustrates an electric circuit diagram for a feeding apparatus according to the invention.

FIG. 2. shows a feeding apparatus according to the in- Vention adapted to be connected to a three-phase network.

FIG. 3 shows a detail of the diagram according to FIG. 1.

FIG. 4 is a graph illustrating the operation of the feeding apparatus according to FIG. 1.

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FIG. 5 illustrates an ignition device according to the present invention for a customary discharge tube.

In conformity with the present invention, the tube is connected to an alternating current network with a rectifier arrangement interposed while the heretofore customary energy storing elements, such as chokes or condensers are eliminated. The rectifier arrangement consists at least in part, of controllable semi-conductors and of a control device adapted to make the semi-conductors conductive, said control device being adapted to vary the time delay relative to the respective zero points of the alternating network voltage.

Advantageously, as controllable semi-conductors, transistors or thyristors are utilized. With the variable time delay of the control apparatus, a phase control can be obtained which permits a variation of the light intensity within wide limits.

According to a further development of the present invention, between two discharge impulses which occur during each semi-cycle at a certain phase angle determined by the time delay, the ionizing condition of the discharge tube is not completely eliminated. It is rather intended in the discharge tubes to maintain a holding current which fiows in the same direction as the discharge impulses but is considerably less relative thereto. To this end, it is provided in conformity with the present invention that parallel to the rectifier arrangement which contains the controllable semi-conductors there is provided at least one noncontrollable rectifier and one limiting resistor serially arranged with said rectifier while the resistance value of said resistor is so dimensioned that also during the blocking condition of the controllable semi-conductor a holding current can flow which will assure the ionizing condition. When the controllable semi-conductor elements together with the output diodes are connected in a bridge circuit, auxiliary rectifiers serving for maintaining the holding current and the series resistor for said auxiliary rectifiers will form merely a parallel current path to the controllable semi-conductor elements.

Referring now to the drawings in detail, the embodiment shown in FIG. 1 is intended for a one-phase operation ou an alternating current network of 220 volts, the phasing conductor of which is designated with the letter R, while its zero conductor is designated with the letter N. The Xenon tube E is connectable directly to the alternating current network through the intervention of a controllable rectifier B while the heretofore customary condensers or chokes acting as energy storing means have been eliminated. As will be evident from FIG. 3 the controllable rectifier bridge comprises two thyristors TH1 and THZ which may also be called controlled rectifiers, gated rectifiers, or silicon controlled rectifiers, and furthermore comprises two noncontrollable diodes D1 and D2 which together with the thyristor are connected in a Gratz circuit. They furnish to the diagonal points 10 and 11 of the bridge the feeding voltage for the discharging tube E. Tube E has an igniting electrode Z which will be further described in connection with FIG. 5. Said electrode Z eX- tends parallel to the vessel wall G surrounding the discharging path, and in communication with a high voltage igniting device D which is likewise connected to the alternating current network RN.

For purposes of changing the light intensity of the discharge tube E the discharge path of which may be made current conductive with each semi-wave of the network alternating voltage and works in impulse operation, there is provided a control apparatus C which each time after a delaying time following the respective passage through the zero points of the network alternating voltage (said delaying time being indicated by Tv in FIG. 4) furnishes a release impulse to the control electrodes S1 and S2 of the thyristors TH1 and THZ and makes the same current conductive. During the time period Ta indicated in FIG. 4 by inclined shading, the alternately conductive thyristors feed impulse light discharge current I to the discharge tube E. The current I flowing through the discharge tube E thus equals an impulse sequence with the frequency of 100 hertz, the thyristors turning off each time when the network voltage periodically reaches the value zero.

The control apparatus C for releasing the thyristors may in a manner known per se comprise a uni-junction transistor which is coupled to a monostable multi-vibrator with variable impulse duration which latter furnishes the adjustable delaying time Tv. This delaying time may, in a manner known per se, be controlled by a variable voltage which makes possible a manual or automatic variation in the delaying time, and consequently a variation of the time medium value of the light intensity furnished by the discharging tube. By means of suitable control devices, this control voltage may be so varied that the light intensity, also when the alternating voltage of the network is changed or when the light intensity of the discharge lamp decreases in view of age, a light intensity will be obtained which remains constant.

In order to avoid that the discharging tube E will between two current impulses (indicated by shading lines in FIG. 4), lose the ionizing condition which, in turn, would result in the fact for the next current impulse the ionizing condition would have to be renewed by connecting the igniting electrode Z to high voltage, with the shading apparatus according to the invention care is taken to the effect that the ionizing condition between two successive discharging current impulses I cannot collapse. To this end, there is provided the auxiliary rectifier arrangement A shown in FIG. 1. During these intervals, a holding current is conveyed to the discharging pipe through said auxiliary rectifier arrangement. While said holding current is very much less than the discharging impulses I furnishing the light impulses, it will still be sufiicient to maintain the ionizing condition. As indicated in FIG. 3, this auxiliary rectifier may be built up by an arrangement according to which parallel to one of the thyristors and in the same passage direction as the latter there is provided a non-controllable rectifier D10, D11. This rectifier together with a series resistor R1, R2 forms a shunt to the thyristor which will assure said holding current as long as said thyristor during the variable delaying time T, remains in its blocking condition.

When high light outputs are required, advantageously, the feeding apparatus is employed which is shown in FIG. 2 and intended for a three-phase circuit. This feeding apparatus furnishes a symmetric load of the three-phase network determined by its three-phase conductors R, S, T. More specifically, the feeding apparatus comprises three controllable rectiers, namely, the three thyristors TH1, THZ, and THS, which together with the three non-controllable rectifiers D4, D5 and D6, in the form of a threephase bridge are connected with the phase conductors of the three-phase network. Each of the three thyristors may, by means of a control device, not shown in FIG. 2, be released with a variable time delay relative to the phase voltage thereon, and will then yield a discharge current impulse I in discharge tube E as illustrated in FIG. 4.

Similar to the embodiment described above, the release of the thyristors may be varied by a direct current or a direct voltage which acts upon three uni-junction triggers respectively connected to a thyristor.

The holding current for maintaining the ionizing condition in the discharge tube is, in a simple manner, produced by providing in parallel to each of the thyristors a diode D10, D11, D12, respectively with a series resistor R1, R2, and R3. With the three-phase feeding on a 220/l 380 v. network as provided for the embodiment of FIG. 2, the employed voltages are sufficiently high to feed two discharge tubes E in series. However, similar to the embodiment of FIG. l, it is necessary to first bring about the ionizing condition than a starting ignition, said ionizing condition being adapted to be maintained by the diodes D10, D11, D12. To this end, there has been provided a high voltage starting device which is shown in FIG. 2 at St, said high voltage starting device being connected to the igniting electrode Z. The operation with two serially arranged discharging pipes E will for a safe first ignition ionizing of said discharging tubes E require a higher voltage than that which is furnished by the network through the diodes D4, D5, D6; D10, D11, D12. Therefore, an additional auxiliary voltage source H with approximately 600 volts is provided which during the starting period is connected to an electrode of the discharging tube E. The diode D7 arranged in series with the discharging tube E separates the auxiliary voltage H from the diodes D4, D5, and D6, which otherwise would, during the starting period, be subjected to a non-permissible high inverse voltage.

After the igniting process has been realized, the auxiliary voltage source H may be switched off. The diode D7 will then operate in conductive condition and will be passed through by the same current as the discharge tube E.

More specifically, such outer igniting system as shown in FIG. 5 can be realized in a simple manner so that the xenon tubes on the market can be employed without -material changes. Tests have shown that the ignition which brings about the ionizing can very well be realized by sending impulses at high voltage of, for instance, from 6 to 8 kv. to a thin electrode which is arranged along its length on the outside of the tube vessel. Such vessel of a Xenon pipe which surrounds the discharging path of the tube is illustrated at 20 in FIG. 5. The xenon tube is mounted in a reflector 21.

As igniting electrode, there may be employed a band 22 of stainless steel ywhich at its ends is connected in glass passages 23 and 24 and the central section of which extends parallel to the longitudinal axis of the Xenon tube.

A particular advantage is obtained due to the fact that the series diode D7 has its anode connected to one of the electrodes of the discharge tube E, whereas its cathode leads to the interconnected anodes of three rectifiers D4, D5, D6, respectively connected to a phase conductor R, S, T, of a three-phase network. In this instance, with the customary network voltages, two discharge lamps can be arranged in series with regard to each other without endangering the diodes D4, D5, D6, by the igniting voltage requiring during the starting period and furnished by the auxiliary voltage source H.

With the arrangement according to the present invention, the auxiliary voltage source may be continuously connected. Inasmuch as the starter always on one side is located to a zero potential, practically no special safety steps and devices are necessary.

With reference to the control of the multivibrator, indicated at C in FIG. 1, a control element K is shown connected thereto. As explained, control element K could be in the form of a manually adjustable circuit component of the multivibrator, or it could be under the control of the voltage of the alternating current supply.

Still further, control element K could be light sensitive so as to respond to the amount of light emanating from the xenon tube or tubes. When control element K is sensitive to the supply voltage or to light falling thereon, it can serve to maintain the emanated light substantially constant. The manual control of the amount of light from the tubes and the automatic control to maintain the adjusted amount of light substantially constant could, of course, be confined into a single control device, if so desired.

*It is, of course, to be understood that the present invention is, by no means, limited to the particular arrangements shown in the drawings, but also comprises any modifications within the scope of the invention.

What is claimed is:

1. A circuit for controlling the operation of a gas discharge Xenon tube having terminals; Ian alternating current supply line, rectifier means in series with the terminals of said tube and said supply line, said rectifier means comprising controllable rectifier elements having control terminal means, impulse generating means connected to said control terminal means and operable to supply impulses to said control terminal means, said impulse generating means including control means operable for determining the time delay between a zero point of the alternating current supplied to said rectifier means and the rise of the respective impulse to said control terminal means, and ignition means for said tube.

2. A circuit according to claim 1 in which said rectifier means forms a bridge with the alternating current supply being connected to opposite corners and diagonally paired terminals thereof, and said rectifier means in each of two adjacent legs of the bridge Iare connected to other diagonal corners thereof.

3. A circuit according to claim 2 in which a diode is connected in parallel with each said rectifier means, and a resistor is in series with each diode, the resistor being of such a size as to maintain ionizing current in said tube during off periods of said rectifier means.

4. A circuit according to claim 1 in which said tube comprises a glass envelope and an igniting electrode on the outside of and adjacent to Isaid envelope.

5. A circuit according to claim 4 which includes a further diode serially connected to one terminal of said tube, and a source of ignitng voltage connected between said one terminal of said tube and said ignitng electrode.

6. A circuit according to claim 4 in which pressurizing means presses said ignitng electrode resiliently against the outside of said envelope.

7. A circuit according. to claim 4 in which said alternating current supply is polyphase, and has a plurality of phase wires and a neutral wire; said rectifier means comprising a said controlled rectifier element between each phase wire and one of the terminals of said tube, a diode and a resistor in series therewith connected in parallel with each controlled rectifier element, a further diode having one side connected to the other terminal of said tube, another further diode connected between the other side of said further diode and each of said phase wires, said ignitng means comprising an ignitng electrode outside said tube, and a source of ignitng voltage connected between said ignitng electrode andthe said other terminal of said tube.

8. A circuit according to claim 7 in which said 4further diode is disposed with its anode connected to said one terminal of said tube, said source of ignitng voltage having its negative terminal connected to said one terminal of said tube and its positive terminal connected to said neutral wire, and said ignitng electrode also being connected tosaid neutral wire.

9. A circuit according to claim 1 in which said impulse generating means comprises a monostable multivibrator having its -output side connected to said control terminal means.

References Cited UNITED STATES PATENTS 3,156,826 11/ 1964 Mutschler 2'50-199 3,23 5,769 2/ 1966 Wattenbach 315-176 3,323,012 5/1967 Seib 315-174 3,265,930 8/1966 Powell 315-209 3,454,865 7/1969 Ellert 323-22 3,358,186 12/1967 Nomura S15-194 3,361,931 1/1968 Vollrath 315-158 JOHN HUCKERT, Primary Examiner S. BRODER, Assistant Examiner U.S. Cl. X.R. 315-199, .209 

